Furnace pressure regulator



Aug, 2, 1932. A. STEINBART FURNACE PRESSURE REGULATOR Filed April 17,1931 2 Sheets-Sheet l Aug. 2, 1932. A. STEINBART FURNACE PRESSUREREGULATOR 2 Shets-Sheet 2 Filed April 17. 1931 144156550 57Z7/V54ET, v

Patented Aug 2;. 1%32 entree ALFRED STEWART, @F PITTSBURGH, PENNSYLVANIAFURNACE PRESSURE REGUEATOR Application. filed April 17, 1931. serial No.530,995,

This invention relates to furnace pressure regulators and while notlimited thereto, relates more particularly to means for and method ofmaintaining a balanced pressure in open-hearth furnaces and the like.

in the operation of opemhearth and similar furnaces it is desirable tomaintain the same pressure in the hearth as the atmospheric pressureoutside in order to economize on fuel and to develop the highesttemperature. l V hen thepressure in the furnace is less thanatmospheric, cold air will flow into the furnace through the doors andother openings and cool the hearth, but if the pressure in the furnaceis higher than atmospheric the hot gases will leak out through theopenings and be lost-0 The outflow of hot gases from the furnace damagesthe door frames and other parts with which they come in contact and alsoare objectionable in the buildings in which the furnaces are located.

A balanced pressure in a furnace is a pressure in the furnace the sameas the atmosr pheric pressure outside.

The present invention has for its object the provision of means forautomatically controlling the furnace draft so as to maintain a balancedpressure in the furnace.

in the drawings:

Figure 1 is an elevation of apparatus constructed in accordance withthis invention.

Figure 2 is an enlarged fragmentary view, partly in section, of thefurnace or hot end of the apparatus.

Figure 3 is an enlarged View, partly in section, of the cold end of theapparatus.

Referring more particularly to the drawings, the numeral 2 designates anopenhearth furnace which is provided with an opening 2 in its wallthrough which. hot gases may escape from the furnace and air may enterthe furnace in accordance to unbalanced pressure between the interior ofthe furnace and the atmosphere.

A pipe 3 is mounted in the opening or port 2* and is provided with aport or orifice 3 in its side wall which communicates with the hot endof a suction tube a which is provided with a restriction wall 5 adjacentits other or cold end, having an outlet orifice 5 therein similar to theorifice 3. The orifices 3 and 5 are only a fraction of the diameter ofthe tube or pipe 4. The pipe e continues beyond the ,IQStIlCtlOIl wall 5and is connected to a conduit 6 having a valve 6* therein.

The conduit 6 communicates with a suction header 7 which may, serve aplurality of suction tubes from diherent furnaces, if desired.

The suction in the header 7 is created by a (5 station 18 which includesa steam jet enhaust-e'r 1? controlled by a valve 20.. The valve 20 isautomatically controlled by rods 21 and 21 connected to an oil-sealedbell 19. The bell'l9 is located'in a vessel 22 which is connected by aT-titting 25 to the pipe26 which is, in turn, connected to the header 7.The rod 21 carries a counterweight if the suction created by theenhauster l7 acting on the bell l9 overcomes the combined weights of thebell and counterweight 23, the bell rises and the rods 21 and 21 operatethe valve 20 to throttle the suction, thereby maintaining a constantsuction in the header .7.

A by-pass conduit 8 is provided between the suction tube or pipe l andthe conduit 6 and is provided with a valve 8 The suction in the tube orpipe l is adapted to be communicated through a pipe 9, having a valve10, to an oil-sealed bell 12 which is carried on one end of a scale beam12*. The other end of the scale beam carries an oil-sealed bell 12 whichis open to the atmosphere through a pipe 29. The end of the beam 12 onwhich the bell 12 is carried is also anchored to a fixed point of thehousthe suction acting on the bell 12 and it is so adjusted that itkeeps the scale beam 12 in a horizontalofr balanced position when thetemperature of gases entering the inlet ori lice 3 is about 1000 degreesFahrenheit.

The scale beam l2 is connected by levers 30 and 31 to a valve 32 of acompressed air motor 13 which has its piston rod is con- All?) nected bya cable or rope 15 to the damper 16 in the draft flue 16 of the furance2.

In operation, with the by-pass valve 8 closed and the valve 6 opensuction from the header 7 will draw gases or air from the conduit 4through the orifice 5 This suction will cause a flow of gases or airthrough the inlet orifice 3 into the suction tube 4. The suction in thepipe or tube 4 will increase until the same weight of gas enters intothe tube 4 through the orifice 3 as is withdrawn through the orifice 5*.After this equilibrium is established the suction in the tube 4 remainsconstant as long as the suction in the header 7 remains constant and thetem-.

perature of the gases flowing through both orifices 3 and 5 remainsconstant. The teniperature at the outlet orifice 5 is atmospheric and,therefore, may be considered constant for practical purposes. Thetemperature at the inlet orifice 3 however, varies very much as at timesthe hot gas from the furnace flows to the inlet orifice and at othertimes cold air which is drawn into the furnace and passes through thepipe 3 flows to the inlet orifice. Furnace gases and air havesubstantially the same density at atmospheric temperature but the gasesat say 2000 degrees Fahrenheit have only 21 per cent. of the density ofatmospheric air. As a result, much lessvweight of gases enters the inletorifice when hot furnace gases are entering and, therefore, the suctionin the tube 4 rises immediately and drops again when cold air enters.

The suction in the tube or pipe 4 is communicated through the pipe 9 tothe bell 12. The variation in the suction or tension of the gas or airin the tube 4 therefore rocks the scale beam 12 which in turn operatesthe valve 32 of the air motor 13 through the rods 30 and 31. Theoperation of the valve 32 controls the motor 13 to open or close thedamper 16 in the draft flue 16*.

When the pressure in the furnace rises and the hot gases issue from thefurnace through the opening 2'* and pipe 3 the suction in the tube 4rises, the bell 12 lowers and the motor 13 opens the damper 16, and whenthe pressure in the furnace goes below atmospheric pressure cold airpasses into the furnace through the pipe 3, the suction in the tube 4drops and the bell 12 rises and the motor 13 is o erated to close thedamper 16.

The action of the damper is gradual and the apparatus is so arrangedthat the damper does not overrun its proper position. The valves 6 and 8are provided for hand control of the damper during bottom'making in thefurnace 2. By closing the valve 6 and hand manipulating the valve 8 themotor 13 can be controlled to operate the damper 16 at will.

While I have shown and described one specific embodiment of my inventionit will aeeaaea be understood that I do not wish to be limited theretosince various modifications may be made without departing from the scopethereof, as defined in the appended claims.

I claim: J L

1. The method of automatically maintaining balanced pressure in afurnace, which consists in allowing hot gases from the furnace to issuefrom an opening when the pressure in the furnace is above atmosphericpressure and allowing cold air to stream into the furnace through thesaid opening when the pressure in the furnace is below atmosphericpressure and using the variation in density of the hot furnace gases andcold air passing through said opening to regulate the draft.

2. The method of automatically maintaining balanced pressure in afurnace, which consists in allowing hot gases from the furnace to issuefrom an opening when the pressure in the furnace is above atmospheric,and allowing cold air to stream into the furnace through the saidopening when the pressure in the furnace is below atmospheric pressure,drawing the air and hotfurnace gases successively through spacedorifices in a confined fiow path causing the hot gases to cool toatmospheric tempera-' ture between said orifices so as to vary thesuction in said flow? path and using the varia-.

tion in suction to operate valves for the regulation of the draft.

3. The method of automatically maintaining balanced pressure in afurnace which consists in allowing hot gases from the furnace to issuefrom an opening when the pressure in the furnace is above atmosphericpressure and allowing cold air to streain into the furnace through saidopening when the pressure in the furnace is below atmospheric pressure,drawing the air and hot furnace gases successively through spacedorifices in a confined flow path of sufficient length to permit the hotfurnace gases to cool to substantiall atmospheric temperature betweensaid 011- fices so as to increase the suction in said flow path when hotfurnace gases are passing therethrough materially above the suction whenair is passing therethrough, and using the variations in suction in saidflow path to regulate the furnace draft.

4. The combination with a furnace having an opening therein throughwhich hot gases will issue rom the furnace when the furnace is operatingabove atmospheric pressure and through which cold air will flow into thefurnace when the furnace is operating below amospheric pressure, of adraft damper for controllin the draft to said furnace, and a suction tue having one end in communication with said opening and its other endmaterial distance from said opening so to maintain said last named endat substantially atmospheric tempere ure, said tube having relativelysmall restr.cted orifices jacent its ends, means for creating a constantsuction at the end of, said tube remote from said furnace to cause aflow of the air and hot furnace gases flowing through said opening intosaid tube through the orifice at the furnace end thereofand out throughthe orifice at the end remote from said furnace, whereby the suction insaid tube will vary with the variations in temperature of said air andhot gases, and means operable by the suction in said tube forautomatically operating said draft damper.

5. The combination with a furnace having an opanin therein through whichhot gases will issue mm the furnace when the furnace is operating aboveatmospheric pressure and through which cold air will flow into thefurnace when the furnace is operating below atmospheric pressure, of adraft damper for controllin the draft to said furnace and a suction tu ehaving one end in communication with said opening and its other endremote from said opening so as to maintain said remote end atsubstantially atmospheric temperature, said tube having relatively smallrestricted orifices adjacent its ends, means for creating a constantsuction at the end of said tube remote from said furnace to cause a flowof the air and hot furnace gases flowing through said opening into saidtube through the orifice at the furnace end thereof and out through theorifice at the end remote from said furnace, whereby the suction in saidtube will vary with the variations in temperature of said air and hotgases, a fluid motor for operating said draft damper, a valve forcontrolling said motor and means operable by the suction in said tubefor automatically operating said valve.

my hand.

ALFRED STEINBART.

In testimony whereof, I have hereunto set

